U.S. Patent Application Publication 2013/0207970, whose disclosure is incorporated herein by reference, describes a scanning depth engine, which includes a transmitter, which emits a beam comprising pulses of light, and a scanner, which is configured to scan the beam, within a predefined scan range, over a scene. A receiver receives the light reflected from the scene and generates an output indicative of the time of flight of the pulses to and from points in the scene. A processor is coupled to control the scanner and to process the output of the receiver so as to generate a 3D map of the scene.
In one of the embodiments disclosed in the above-mentioned publication, the light from the transmitter reflects off a beamsplitter and is then directed by a turning mirror (also referred to as a folding mirror) toward a scanning micromirror. Light pulses returned from the scene strike the micromirror, which reflects the light via the turning mirror through the beamsplitter to the receiver. The beamsplitter may have a bandpass coating, to prevent light outside the emission band of the transmitter from reaching the receiver.